An carrier-grade network address translation (Carrier-Grade Network Address Translation, CGN) device is located within a carrier, located at the boundary between a public network and a private network, and used for providing high-performance translation from a private address of an Internet protocol version 4 (Internet Protocol Version 4, IPv4) to a public address of IPv4; public network IPv4 addresses can be saved effectively while it is implemented that a private network user accesses the public network; the speed of consuming the IPv4 addresses can be slowed down by using the CGN technology, so as to get prepared for true transition to an Internet protocol version 6 (Internet Protocol Version 6, IPv6). Currently, the CGN device manages a public IP address based on a CGN board. It is required to statically configure a public IP address pool for every CGN board in advance. When a user goes on-line through a certain CGN board, the CGN board allocates a public IP address to the user through the pre-configured public IP address pool on the CGN board. When the user's traffic load sharing between CGN boards is unbalanced, it appears that the pre-configured public IP addresses of some CGN boards are exhausted while many pre-configured public IP address pools of some CGN boards are idle, so as to result in the waste and the low utilization ratio of the public IP addresses.